Internal base plate for instrument transformers



May 23, 1967 F. R. DENTREMONT INTERNAL BASE PLATE FOR INSTRUMENTTRANSFORMERS Filed July 12, 1965 United States Patent Ofi 3,321,168Patented May 23, 1967 s 321 168 INTERNAL BASE PiATE FOR INSTRUMENTTRANSFORMERS Franklin R. DEntremont, Dover, N.H., assignor to Gen- Thisinvention relates to instrument transformers and more particularly to aninternal base plate for an instrument transformer.

In recent years it has become a common practice in the instrumenttransformer field to completely enclose the various parts of instrumenttransformers in a molded plastic body. The plastic body provides theinsulation between the various parts of the transformer and also formsthe outer casing or housing for the transformer. An example of suchtransformer is found in Patent No. 2,618,689.

In these molded transformers, various problems have been noted inattempting to mount the transformer for use. One mounting means whichhas been used includes a pair of metallic strap members which encirclethe transformer. These strap members are secured to a base plate or amounting plate by means of bolts or the like. These types of mountingsare generally considered undesirable due to the relatively high laborcost required to assemble the mounting means to the transformer. Anothersolution which has been tried is to mold the base plate into the base ofthe transformer, embedding it in the plastic body member. Various ofthese base plates have been unsuccessful in that only a very thin layerof plastic material is available to hold the base plate to the bodymember. When the mounted transformer is subjected to vibration ormechanical shock, the transformer has tended to separate from the baseplate.

Therefore, it is one object of this invention to provide a novel baseplate for instrument transformers.

A further object of this invention is to provide an internal base platewhich may be molded in the body of an instrument transformer.

A still further object of this invention is to provide a novel internalbase plate for an instrument transformer which will be securely lockedin the molded body thereof.

In carrying out this invention in one form, a base plate for aninstrument transformer is provided in the form of a rectangular metallicplate. The metallic plate has a pair of upstanding flanges on oppositesides of the plate, each flange having a plurality of holestherethrough.

When the base plate is molded in the plastic body of a transformer, theplastic material flows through the plurality of holes, and when cured,securely attaches or locks the base plate to the plastic body. Aplurality of bosses are provided extending from the metallic plate in adirection opposite the upstanding flanges. These bosses are providedwith tapped holes for mounting the transformer to any desired mountingbracket.

The invention which is sought to be protected will be particularlypointed out and distinctly claimed in the claims appended hereto.However, it is believed that this invention and the manner in which itsvarious objects and advantages are obtained, as well as other objectsand advantages thereof, will be more clearly understood from thefollowing detailed description of a preferred embodiment thereof,particularly when considered in the light of the accompanying drawing,in which:

FIGURE 1 is an end view of an instrument transformer showing one form ofbase plate according to this invention;

FIGURE 2 is an enlarged sectional view of a portion of a transformer andbase plate showing further features of this invention in greater detail;

FIGURE 3 is a perspective view of one form of base plate according tothis invention; and

FIGURE 4 is a sectional view taken on the line 4-4 of FIG. 3.

Reference will now be made to the drawing in which like numerals areused to indicate like parts, throughout the various views thereof. InFIG. 1 there is shown an end view of an instrument transformer 10 whichcomprises a core and coil unit 12, the core and coil unit 12 beingcontained or embedded in a molded plastic body 14. As shown, a windowopening 18 is provided in the core and coil unit 12 and the plasticmaterial is molded about the core and coil unit to provide a windowopening 20 in the body 14. A primary bar member 22 may be mounted inwindow opening 20 in a manner well understood. Also, the secondaryterminals 24 and 26 are provided on top of the body 14, as shown. Inaccordance with this invention a base plate 28 is provided, molded inthe plastic body 14 as shown. Bosses 30 are provided on base plate 28and may be tapped to receive bolts 32. As shown, bolts 32 are used toattach the instrument transformer 10 to a mounting plate 34.

A preferred form of base plate 28 isbest shown in FIGS. 3, and 4 of thedrawing. As there shown, the base plate 28 is preferably in the form ofa rectangular metallic plate having a central portion 36 and upstandingflanges 38 and 40 on opposite ends thereof. Each of flanges 38 and 40 isprovided with a plurality of holes 42 extending through the flanges 38and 40, as is clearly shown in the drawing. A plurality of bosses 30 areformed on the bottom of the central portion 36 of base plate 28. Thesebosses extend from base plate 28 in a direction opposite to theupstanding flanges 38 and 40. Bosses 30 have tapped holes 44 therein forsecuring the base plate 28, and therefore, the transformer 10, to anydesired mounting means. In the preferred form of base plate according tothis invention the central portion 36 has a curved channel 46 with anopening 48 therein. The opening 48 allows a portion of the core and coilunit of the instrument transformer to extend therethrough. This allowsthe base plate 28 to be embedded in the plastic body 14 withoutunnecessarily increasing the thickness of the plastic material below thecore and coil unit 12. Of course, the plastic material of body 14 willextend between the core and coil unit 12 and the edges of opening 48 inthe base plate 28 providing the desired insulation between the core andcoil unit 12 and the base plate-28.

As will be apparent from the above description, the base plate 28 isembedded in the plastic body 14 with the upturned flanges 38 and 40extending in to the body 14. The base plate 28 and the core and coilunit 12 will be mounted in the desired relative position in a mold, anda plastic material for the body 14 will be poured into such mold. Thisplastic material will flow around the upturned flanges 38 and 40 andthrough holes 42. As will be understood, threaded plugs will be providedin tapped holes 44 during molding to prevent the plastic materialflowing into these holes. As will be apparent, when the plastic materialis cured, integral locking portions will be provided extending throughthe holes 42. This is more clearly shown in FIG. 2 of the drawing.

As can be seen in FIG. 2, the plastic material of body '14 extendsthrough the hole 42 in the flange 40 and is integral with the plasticmaterial on both sides of the flange 40. Obviously, this same integrallocking will be obtained through each of holes 42 on both of flanges 38and 40. The bosses 30 are generally provided flush with the bottom ofthe molded body 14 in the manner shown in FIG. 2. Thus a mounting means,such as mounting member 34, may be readily attached to the base plate 328 by the bolts 32. This of course will firmly attach the transformer 10to the mounting means.

While there has been shown and described the present preferredembodiment of the internal base plate of this invention, it will beobvious to those skilled in the art that various changes may be made inthe structural details thereof. openings could be provided in theupturned flanges. The opening 48 in the base plate could be eliminated,if desired, and a greater thickness of material provided on the lowerportion of the transformer. Obviously, these and other changes may bemade without departing from the spirit and scope of the invention as setforth in the appended claims.

What is claimed as new and which it is desired to secure by LettersPatent of the United States is:

1. A base plate for an instrument transformer comprising: asubstantially rectangular metallic plate member, a pair of upturnedflanges on opposite sides of said plate member, said upturned flangesprovided with a plu- -rality of holes therethrough, and a plurality ofbosses on said plate member, said bosses extending from said platemember in a direction opposite to said upturned flanges, said bosseshaving tapped holes therein.

2. A base plate as claimed in claim 1 in which the central portion ofthe metallic plate member is provided with an opening the-rethrough forthe entry of the core and coil unit of an instrument transformer.

For example, a more or less number of 3. An instrument transformerhaving an internal base plate, comprising in combination, a moldedplastic body for said transformer, a substantially rectangular metal-licplate member molded into said molded body, said metallic plate having apair of upturned flanges on opposite sides of said plate, said flangesprovided with a plurality of holes therethrough, the plastic material ofsaid molded body extending through said holes for securing said metallicplate in said molded body and a plurality of bosses on said plate,extending from said plate in'a direction opposite said flanges, saidbosses being provided with tapped holes for mounting to a mountingbracket.

References Cited by the Examiner UNITED STATES PATENTS 1,877,064 9/ 1932Schultz 248350 2,618,689 11/1952 Cook 336 2,930,011 '3/ 1960 Wigert etal. 33696 3,024,434 '3/ 1962 Carson 33696 3,092,364 6/1963 Sa-rafinos248-350 3,202,947 8/ 1965 Budovac 326-96 JOHN PETO, Primary Examiner.

CLAUDE A. LEROY, Examiner.

I. F. FOSS, Assistant Examiner.

1. A BASE PLATE FOR AN INSTRUMENT TRANSFORMER COMPRISING: ASUBSTANTIALLY RECTANGULAR METALLIC PLATE MEMBER, A PAIR OF UPTURNEDFLANGES ON OPPOSITE SIDES OF SAID PLATE MEMBER, SAID UPTURNED FLANGESPROVIDED WITH A PLURALITY OF HOLES THERETHROUGH, AND A PLURALITY OFBOSSES ON SAID PLATE MEMBER, SAID BOSSES EXTENDING FROM SAID PLATEMEMBER IN A DIRECTION OPPOSITE TO SAID UPTURNED FLANGES, SAID BOSSESHAVING TAPPED HOLES THEREIN.